CE Smith Flush Mount Rod Holder, 70 Series-Replacement Parts and Accessories for Tournament Fishing,  Rod Fishing, Deep Sea Fishing and Trolling 316L Stainless - Mirror Polished 9in Long Tube is 1-5/8in ID x 2in OD Rounded cast bottom with integrally cast 1/4in wide x 1/2in tall gimbal bar and 1/2in threaded drain hole The flange is 4-1/2in long x 3-5/8in wide 30 Degrees from Vertical